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1 /* $OpenBSD: queue.h,v 1.17 2000/11/16 20:02:20 provos Exp $ */
2 /* $NetBSD: queue.h,v 1.11 1996/05/16 05:17:14 mycroft Exp $ */
3
4 /*
5 * Copyright (c) 1991, 1993
6 * The Regents of the University of California. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. All advertising materials mentioning features or use of this software
17 * must display the following acknowledgement:
18 * This product includes software developed by the University of
19 * California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * @(#)queue.h 8.5 (Berkeley) 8/20/94
37 */
38
39 #ifndef _SYS_QUEUE_H_
40 #define _SYS_QUEUE_H_
41
42 /*
43 * This file defines five types of data structures: singly-linked lists,
44 * lists, simple queues, tail queues, and circular queues.
45 *
46 *
47 * A singly-linked list is headed by a single forward pointer. The elements
48 * are singly linked for minimum space and pointer manipulation overhead at
49 * the expense of O(n) removal for arbitrary elements. New elements can be
50 * added to the list after an existing element or at the head of the list.
51 * Elements being removed from the head of the list should use the explicit
52 * macro for this purpose for optimum efficiency. A singly-linked list may
53 * only be traversed in the forward direction. Singly-linked lists are ideal
54 * for applications with large datasets and few or no removals or for
55 * implementing a LIFO queue.
56 *
57 * A list is headed by a single forward pointer (or an array of forward
58 * pointers for a hash table header). The elements are doubly linked
59 * so that an arbitrary element can be removed without a need to
60 * traverse the list. New elements can be added to the list before
61 * or after an existing element or at the head of the list. A list
62 * may only be traversed in the forward direction.
63 *
64 * A simple queue is headed by a pair of pointers, one the head of the
65 * list and the other to the tail of the list. The elements are singly
66 * linked to save space, so elements can only be removed from the
67 * head of the list. New elements can be added to the list before or after
68 * an existing element, at the head of the list, or at the end of the
69 * list. A simple queue may only be traversed in the forward direction.
70 *
71 * A tail queue is headed by a pair of pointers, one to the head of the
72 * list and the other to the tail of the list. The elements are doubly
73 * linked so that an arbitrary element can be removed without a need to
74 * traverse the list. New elements can be added to the list before or
75 * after an existing element, at the head of the list, or at the end of
76 * the list. A tail queue may be traversed in either direction.
77 *
78 * A circle queue is headed by a pair of pointers, one to the head of the
79 * list and the other to the tail of the list. The elements are doubly
80 * linked so that an arbitrary element can be removed without a need to
81 * traverse the list. New elements can be added to the list before or after
82 * an existing element, at the head of the list, or at the end of the list.
83 * A circle queue may be traversed in either direction, but has a more
84 * complex end of list detection.
85 *
86 * For details on the use of these macros, see the queue(3) manual page.
87 */
88
89 /*
90 * Singly-linked List definitions.
91 */
92 #define SLIST_HEAD(name, type) \
93 struct name { \
94 struct type *slh_first; /* first element */ \
95 }
96
97 #define SLIST_HEAD_INITIALIZER(head) \
98 { NULL }
99
100 #define SLIST_ENTRY(type) \
101 struct { \
102 struct type *sle_next; /* next element */ \
103 }
104
105 /*
106 * Singly-linked List access methods.
107 */
108 #define SLIST_FIRST(head) ((head)->slh_first)
109 #define SLIST_END(head) NULL
110 #define SLIST_EMPTY(head) (SLIST_FIRST(head) == SLIST_END(head))
111 #define SLIST_NEXT(elm, field) ((elm)->field.sle_next)
112
113 #define SLIST_FOREACH(var, head, field) \
114 for((var) = SLIST_FIRST(head); \
115 (var) != SLIST_END(head); \
116 (var) = SLIST_NEXT(var, field))
117
118 /*
119 * Singly-linked List functions.
120 */
121 #define SLIST_INIT(head) { \
122 SLIST_FIRST(head) = SLIST_END(head); \
123 }
124
125 #define SLIST_INSERT_AFTER(slistelm, elm, field) do { \
126 (elm)->field.sle_next = (slistelm)->field.sle_next; \
127 (slistelm)->field.sle_next = (elm); \
128 } while (0)
129
130 #define SLIST_INSERT_HEAD(head, elm, field) do { \
131 (elm)->field.sle_next = (head)->slh_first; \
132 (head)->slh_first = (elm); \
133 } while (0)
134
135 #define SLIST_REMOVE_HEAD(head, field) do { \
136 (head)->slh_first = (head)->slh_first->field.sle_next; \
137 } while (0)
138
139 #define SLIST_REMOVE(head, elm, type, field) do { \
140 if ((head)->slh_first == (elm)) { \
141 SLIST_REMOVE_HEAD((head), field); \
142 } \
143 else { \
144 struct type *curelm = (head)->slh_first; \
145 while( curelm->field.sle_next != (elm) ) \
146 curelm = curelm->field.sle_next; \
147 curelm->field.sle_next = \
148 curelm->field.sle_next->field.sle_next; \
149 } \
150 } while (0)
151
152 /*
153 * List definitions.
154 */
155 #define LIST_HEAD(name, type) \
156 struct name { \
157 struct type *lh_first; /* first element */ \
158 }
159
160 #define LIST_HEAD_INITIALIZER(head) \
161 { NULL }
162
163 #define LIST_ENTRY(type) \
164 struct { \
165 struct type *le_next; /* next element */ \
166 struct type **le_prev; /* address of previous next element */ \
167 }
168
169 /*
170 * List access methods
171 */
172 #define LIST_FIRST(head) ((head)->lh_first)
173 #define LIST_END(head) NULL
174 #define LIST_EMPTY(head) (LIST_FIRST(head) == LIST_END(head))
175 #define LIST_NEXT(elm, field) ((elm)->field.le_next)
176
177 #define LIST_FOREACH(var, head, field) \
178 for((var) = LIST_FIRST(head); \
179 (var)!= LIST_END(head); \
180 (var) = LIST_NEXT(var, field))
181
182 /*
183 * List functions.
184 */
185 #define LIST_INIT(head) do { \
186 LIST_FIRST(head) = LIST_END(head); \
187 } while (0)
188
189 #define LIST_INSERT_AFTER(listelm, elm, field) do { \
190 if (((elm)->field.le_next = (listelm)->field.le_next) != NULL) \
191 (listelm)->field.le_next->field.le_prev = \
192 &(elm)->field.le_next; \
193 (listelm)->field.le_next = (elm); \
194 (elm)->field.le_prev = &(listelm)->field.le_next; \
195 } while (0)
196
197 #define LIST_INSERT_BEFORE(listelm, elm, field) do { \
198 (elm)->field.le_prev = (listelm)->field.le_prev; \
199 (elm)->field.le_next = (listelm); \
200 *(listelm)->field.le_prev = (elm); \
201 (listelm)->field.le_prev = &(elm)->field.le_next; \
202 } while (0)
203
204 #define LIST_INSERT_HEAD(head, elm, field) do { \
205 if (((elm)->field.le_next = (head)->lh_first) != NULL) \
206 (head)->lh_first->field.le_prev = &(elm)->field.le_next;\
207 (head)->lh_first = (elm); \
208 (elm)->field.le_prev = &(head)->lh_first; \
209 } while (0)
210
211 #define LIST_REMOVE(elm, field) do { \
212 if ((elm)->field.le_next != NULL) \
213 (elm)->field.le_next->field.le_prev = \
214 (elm)->field.le_prev; \
215 *(elm)->field.le_prev = (elm)->field.le_next; \
216 } while (0)
217
218 #define LIST_REPLACE(elm, elm2, field) do { \
219 if (((elm2)->field.le_next = (elm)->field.le_next) != NULL) \
220 (elm2)->field.le_next->field.le_prev = \
221 &(elm2)->field.le_next; \
222 (elm2)->field.le_prev = (elm)->field.le_prev; \
223 *(elm2)->field.le_prev = (elm2); \
224 } while (0)
225
226 /*
227 * Simple queue definitions.
228 */
229 #define SIMPLEQ_HEAD(name, type) \
230 struct name { \
231 struct type *sqh_first; /* first element */ \
232 struct type **sqh_last; /* addr of last next element */ \
233 }
234
235 #define SIMPLEQ_HEAD_INITIALIZER(head) \
236 { NULL, &(head).sqh_first }
237
238 #define SIMPLEQ_ENTRY(type) \
239 struct { \
240 struct type *sqe_next; /* next element */ \
241 }
242
243 /*
244 * Simple queue access methods.
245 */
246 #define SIMPLEQ_FIRST(head) ((head)->sqh_first)
247 #define SIMPLEQ_END(head) NULL
248 #define SIMPLEQ_EMPTY(head) (SIMPLEQ_FIRST(head) == SIMPLEQ_END(head))
249 #define SIMPLEQ_NEXT(elm, field) ((elm)->field.sqe_next)
250
251 #define SIMPLEQ_FOREACH(var, head, field) \
252 for((var) = SIMPLEQ_FIRST(head); \
253 (var) != SIMPLEQ_END(head); \
254 (var) = SIMPLEQ_NEXT(var, field))
255
256 /*
257 * Simple queue functions.
258 */
259 #define SIMPLEQ_INIT(head) do { \
260 (head)->sqh_first = NULL; \
261 (head)->sqh_last = &(head)->sqh_first; \
262 } while (0)
263
264 #define SIMPLEQ_INSERT_HEAD(head, elm, field) do { \
265 if (((elm)->field.sqe_next = (head)->sqh_first) == NULL) \
266 (head)->sqh_last = &(elm)->field.sqe_next; \
267 (head)->sqh_first = (elm); \
268 } while (0)
269
270 #define SIMPLEQ_INSERT_TAIL(head, elm, field) do { \
271 (elm)->field.sqe_next = NULL; \
272 *(head)->sqh_last = (elm); \
273 (head)->sqh_last = &(elm)->field.sqe_next; \
274 } while (0)
275
276 #define SIMPLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
277 if (((elm)->field.sqe_next = (listelm)->field.sqe_next) == NULL)\
278 (head)->sqh_last = &(elm)->field.sqe_next; \
279 (listelm)->field.sqe_next = (elm); \
280 } while (0)
281
282 #define SIMPLEQ_REMOVE_HEAD(head, elm, field) do { \
283 if (((head)->sqh_first = (elm)->field.sqe_next) == NULL) \
284 (head)->sqh_last = &(head)->sqh_first; \
285 } while (0)
286
287 /*
288 * Tail queue definitions.
289 */
290 #define TAILQ_HEAD(name, type) \
291 struct name { \
292 struct type *tqh_first; /* first element */ \
293 struct type **tqh_last; /* addr of last next element */ \
294 }
295
296 #define TAILQ_HEAD_INITIALIZER(head) \
297 { NULL, &(head).tqh_first }
298
299 #define TAILQ_ENTRY(type) \
300 struct { \
301 struct type *tqe_next; /* next element */ \
302 struct type **tqe_prev; /* address of previous next element */ \
303 }
304
305 /*
306 * tail queue access methods
307 */
308 #define TAILQ_FIRST(head) ((head)->tqh_first)
309 #define TAILQ_END(head) NULL
310 #define TAILQ_NEXT(elm, field) ((elm)->field.tqe_next)
311 #define TAILQ_LAST(head, headname) \
312 (*(((struct headname *)((head)->tqh_last))->tqh_last))
313 /* XXX */
314 #define TAILQ_PREV(elm, headname, field) \
315 (*(((struct headname *)((elm)->field.tqe_prev))->tqh_last))
316 #define TAILQ_EMPTY(head) \
317 (TAILQ_FIRST(head) == TAILQ_END(head))
318
319 #define TAILQ_FOREACH(var, head, field) \
320 for((var) = TAILQ_FIRST(head); \
321 (var) != TAILQ_END(head); \
322 (var) = TAILQ_NEXT(var, field))
323
324 #define TAILQ_FOREACH_REVERSE(var, head, field, headname) \
325 for((var) = TAILQ_LAST(head, headname); \
326 (var) != TAILQ_END(head); \
327 (var) = TAILQ_PREV(var, headname, field))
328
329 /*
330 * Tail queue functions.
331 */
332 #define TAILQ_INIT(head) do { \
333 (head)->tqh_first = NULL; \
334 (head)->tqh_last = &(head)->tqh_first; \
335 } while (0)
336
337 #define TAILQ_INSERT_HEAD(head, elm, field) do { \
338 if (((elm)->field.tqe_next = (head)->tqh_first) != NULL) \
339 (head)->tqh_first->field.tqe_prev = \
340 &(elm)->field.tqe_next; \
341 else \
342 (head)->tqh_last = &(elm)->field.tqe_next; \
343 (head)->tqh_first = (elm); \
344 (elm)->field.tqe_prev = &(head)->tqh_first; \
345 } while (0)
346
347 #define TAILQ_INSERT_TAIL(head, elm, field) do { \
348 (elm)->field.tqe_next = NULL; \
349 (elm)->field.tqe_prev = (head)->tqh_last; \
350 *(head)->tqh_last = (elm); \
351 (head)->tqh_last = &(elm)->field.tqe_next; \
352 } while (0)
353
354 #define TAILQ_INSERT_AFTER(head, listelm, elm, field) do { \
355 if (((elm)->field.tqe_next = (listelm)->field.tqe_next) != NULL)\
356 (elm)->field.tqe_next->field.tqe_prev = \
357 &(elm)->field.tqe_next; \
358 else \
359 (head)->tqh_last = &(elm)->field.tqe_next; \
360 (listelm)->field.tqe_next = (elm); \
361 (elm)->field.tqe_prev = &(listelm)->field.tqe_next; \
362 } while (0)
363
364 #define TAILQ_INSERT_BEFORE(listelm, elm, field) do { \
365 (elm)->field.tqe_prev = (listelm)->field.tqe_prev; \
366 (elm)->field.tqe_next = (listelm); \
367 *(listelm)->field.tqe_prev = (elm); \
368 (listelm)->field.tqe_prev = &(elm)->field.tqe_next; \
369 } while (0)
370
371 #define TAILQ_REMOVE(head, elm, field) do { \
372 if (((elm)->field.tqe_next) != NULL) \
373 (elm)->field.tqe_next->field.tqe_prev = \
374 (elm)->field.tqe_prev; \
375 else \
376 (head)->tqh_last = (elm)->field.tqe_prev; \
377 *(elm)->field.tqe_prev = (elm)->field.tqe_next; \
378 } while (0)
379
380 #define TAILQ_REPLACE(head, elm, elm2, field) do { \
381 if (((elm2)->field.tqe_next = (elm)->field.tqe_next) != NULL) \
382 (elm2)->field.tqe_next->field.tqe_prev = \
383 &(elm2)->field.tqe_next; \
384 else \
385 (head)->tqh_last = &(elm2)->field.tqe_next; \
386 (elm2)->field.tqe_prev = (elm)->field.tqe_prev; \
387 *(elm2)->field.tqe_prev = (elm2); \
388 } while (0)
389
390 /*
391 * Circular queue definitions.
392 */
393 #define CIRCLEQ_HEAD(name, type) \
394 struct name { \
395 struct type *cqh_first; /* first element */ \
396 struct type *cqh_last; /* last element */ \
397 }
398
399 #define CIRCLEQ_HEAD_INITIALIZER(head) \
400 { CIRCLEQ_END(&head), CIRCLEQ_END(&head) }
401
402 #define CIRCLEQ_ENTRY(type) \
403 struct { \
404 struct type *cqe_next; /* next element */ \
405 struct type *cqe_prev; /* previous element */ \
406 }
407
408 /*
409 * Circular queue access methods
410 */
411 #define CIRCLEQ_FIRST(head) ((head)->cqh_first)
412 #define CIRCLEQ_LAST(head) ((head)->cqh_last)
413 #define CIRCLEQ_END(head) ((void *)(head))
414 #define CIRCLEQ_NEXT(elm, field) ((elm)->field.cqe_next)
415 #define CIRCLEQ_PREV(elm, field) ((elm)->field.cqe_prev)
416 #define CIRCLEQ_EMPTY(head) \
417 (CIRCLEQ_FIRST(head) == CIRCLEQ_END(head))
418
419 #define CIRCLEQ_FOREACH(var, head, field) \
420 for((var) = CIRCLEQ_FIRST(head); \
421 (var) != CIRCLEQ_END(head); \
422 (var) = CIRCLEQ_NEXT(var, field))
423
424 #define CIRCLEQ_FOREACH_REVERSE(var, head, field) \
425 for((var) = CIRCLEQ_LAST(head); \
426 (var) != CIRCLEQ_END(head); \
427 (var) = CIRCLEQ_PREV(var, field))
428
429 /*
430 * Circular queue functions.
431 */
432 #define CIRCLEQ_INIT(head) do { \
433 (head)->cqh_first = CIRCLEQ_END(head); \
434 (head)->cqh_last = CIRCLEQ_END(head); \
435 } while (0)
436
437 #define CIRCLEQ_INSERT_AFTER(head, listelm, elm, field) do { \
438 (elm)->field.cqe_next = (listelm)->field.cqe_next; \
439 (elm)->field.cqe_prev = (listelm); \
440 if ((listelm)->field.cqe_next == CIRCLEQ_END(head)) \
441 (head)->cqh_last = (elm); \
442 else \
443 (listelm)->field.cqe_next->field.cqe_prev = (elm); \
444 (listelm)->field.cqe_next = (elm); \
445 } while (0)
446
447 #define CIRCLEQ_INSERT_BEFORE(head, listelm, elm, field) do { \
448 (elm)->field.cqe_next = (listelm); \
449 (elm)->field.cqe_prev = (listelm)->field.cqe_prev; \
450 if ((listelm)->field.cqe_prev == CIRCLEQ_END(head)) \
451 (head)->cqh_first = (elm); \
452 else \
453 (listelm)->field.cqe_prev->field.cqe_next = (elm); \
454 (listelm)->field.cqe_prev = (elm); \
455 } while (0)
456
457 #define CIRCLEQ_INSERT_HEAD(head, elm, field) do { \
458 (elm)->field.cqe_next = (head)->cqh_first; \
459 (elm)->field.cqe_prev = CIRCLEQ_END(head); \
460 if ((head)->cqh_last == CIRCLEQ_END(head)) \
461 (head)->cqh_last = (elm); \
462 else \
463 (head)->cqh_first->field.cqe_prev = (elm); \
464 (head)->cqh_first = (elm); \
465 } while (0)
466
467 #define CIRCLEQ_INSERT_TAIL(head, elm, field) do { \
468 (elm)->field.cqe_next = CIRCLEQ_END(head); \
469 (elm)->field.cqe_prev = (head)->cqh_last; \
470 if ((head)->cqh_first == CIRCLEQ_END(head)) \
471 (head)->cqh_first = (elm); \
472 else \
473 (head)->cqh_last->field.cqe_next = (elm); \
474 (head)->cqh_last = (elm); \
475 } while (0)
476
477 #define CIRCLEQ_REMOVE(head, elm, field) do { \
478 if ((elm)->field.cqe_next == CIRCLEQ_END(head)) \
479 (head)->cqh_last = (elm)->field.cqe_prev; \
480 else \
481 (elm)->field.cqe_next->field.cqe_prev = \
482 (elm)->field.cqe_prev; \
483 if ((elm)->field.cqe_prev == CIRCLEQ_END(head)) \
484 (head)->cqh_first = (elm)->field.cqe_next; \
485 else \
486 (elm)->field.cqe_prev->field.cqe_next = \
487 (elm)->field.cqe_next; \
488 } while (0)
489
490 #define CIRCLEQ_REPLACE(head, elm, elm2, field) do { \
491 if (((elm2)->field.cqe_next = (elm)->field.cqe_next) == \
492 CIRCLEQ_END(head)) \
493 (head).cqh_last = (elm2); \
494 else \
495 (elm2)->field.cqe_next->field.cqe_prev = (elm2); \
496 if (((elm2)->field.cqe_prev = (elm)->field.cqe_prev) == \
497 CIRCLEQ_END(head)) \
498 (head).cqh_first = (elm2); \
499 else \
500 (elm2)->field.cqe_prev->field.cqe_next = (elm2); \
501 } while (0)
502
503 #endif /* !_SYS_QUEUE_H_ */